Cellular telephone systems are today operational in a large number of cities in the United States and in several foreign countries. These systems were originally designed to provide improved vehicle based, mobile, telephone service. In this type of installation, a transceiver is mounted in a vehicle along with a control head. Telephone calls may be received at the control head in the vehicle or initiated via the control head in the vehicle. The calls are transmitted via radio link to and from the vehicle and to and from an adjacent or nearby cellular base station. Cellular mobile transmission takes place in an 800-900 MHz band. The cellular base station is in turn coupled to a land based telephone system.
As an alternate to mounting a cellular transceiver in a vehicle, it has been found useful and beneficial to use cellular transceivers not only in vehicles but also at remote sites where land line telephone systems cannot be cost effectively or conveniently installed or maintained. For example, cellular transceivers have found use on oil drilling platforms, and in remote geographical areas such as farms, ranches or vacation resorts. Cellular transceivers have also been successfully used on board ships.
In this latter type of installation, it is desirable to be able to use standard telephone equipment in conjunction with the cellular mobile transceiver unit. Such equipment has a two wire loop start interface as opposed to the multi-line digital interfaces of the control heads commonly used in cellular mobile installations. Several types of products have been developed to meet these needs. For example, one interface permits an ordinary telephone to be connected to a cellular mobile transceiver. This interface provides for connection of only one telephone line to the cellular mobile transceiver. This interface includes a wired logic control unit as opposed to a programmable processor.
Another product, is an interface which provides for coupling a computer or other electronic equipment, which could include a telephone, to a cellular mobile transceiver. Such a transceiver could be mounted in a vehicle or could alternately be located at a fixed remote site.
None of the known available systems make full use of the potential of cellular telephone communications to provide telephone service or communication at sites which can then be coupled via the cellular transceiver to a remote land line telephone system. Rural wireless telephone systems are known which operate in conjunction with earlier MTS and IMTS wireless telephone technology. These systems provide service for multiple units locally connected to a transceiver. The transceiver communicates via radio link to a remote land line telephone system. These systems transmit calling digit information to the remote land line system as each digit is received from a locally connected unit. Known rural telephone systems do not provide the improved performance characteristics that are available through the use of cellular telephone systems.
Thus, there continues to be a need for cellular based remote stations which can provide a variety of telephone or data communication services to communication units which are coupled to the cellular transceiver. These units are linked to remote land line telephone systems only via the cellular radio transmission system.